I'll look at that next. I found a blow up diagram for the heating and AC system and it shows the mono valve is only on 82s and forward. Some of the system seems to work. The air will switch from the defrost vents to bi level but not the dash vents. I also notice that the compressor does engage when on defrost or when the AC switch is on. I think it only blows out of the defrost and bilevel because it knows the air is hot. The question is what components control the flow of hot water on the 1981 models.

Thanks for the in put.